Fluorine-containing compounds have been continuously used or developed in wide application fields centering on the field of advanced materials from characteristics of fluorine such as water repellency, oil repellency, low water absorption, heat resistance, weather resistance, corrosion resistance, transparency, photosensitivity, low refractive index properties and low dielectric property. In particular, when the characteristics of transparency behavior in each wavelength are utilized, they are used in the coating field. Active researches and developments have been made in the fields of anti-reflection films to which low refractive index properties and transparency of visible light are applied, optical devices to which transparency in a long wavelength band (an optical communication wavelength band) is applied, resist compositions to which transparency in an ultraviolet region (particularly, a vacuum ultraviolet region) is applied, and the like. Recent researches of resist materials have shifted from 248-nm KrF to resists for 193-nm ArF excimer lasers or F2 lasers of the vacuum ultraviolet region represented by 157 nm, and resist materials containing polymer compounds into which acid labile groups are incorporated have been generally designed, the solubility in an alkaline aqueous solution of the acid labile groups being changed by the action of acids.
As the acid labile groups, there are in heavy usage at present a methoxymethyl group, a tert-butyl group and a tert-butyloxycarbonyl group. The resist materials containing those acid labile groups have disadvantages of being large in the outgas amount after exposure, further, not being excellent in resistance to a dry etching gas and transparency in each wavelength, having a low glass transition point, and the like. Specifically, as acidic groups for 157 nm, there have been developed trifluoromethylmethacrylic acid, a hexafluorocarbinol group and a fluorine-containing acidic group such as a fluorine-containing cyclic alcohol. When acid labile groups for protecting those acidic groups are a methoxymethyl group, a tert-butyl group and a tert-butyloxycarbonyl group, there arise the disadvantages of decreasing in etching resistance, decreasing in glass transition point (Tg) and forming an outgas in large amounts, because no ring structure is contained in the acid labile groups. Further, no fluorine atom is contained, so that it has also been impossible to improve transparency. Recently, it has been reported that the use of cyclic hydrocarbon group-containing acid labile groups can improve dry etching resistance (for example, see non-patent document 1). However, adhesion and transparency decrease to the content of the acid labile groups, because of their hydrophobic cyclohexane structure. Consequently, there has been desired the creation of acid labile groups which improve dry etching resistance, enhance transparency in each wavelength used and adhesion to a substrate, and realize a high glass transition point.
Non-Patent Document: S. Kodama, et al., Proceedings of SPIE—The International Society for Optical Engineering (2002), 4690, 76–83